1. Field of the Invention.
This invention pertains to structures that support persons and objects above the ground, and more particularly to apparatus that supports persons and objects in an upright attitude regardless of the ground contour.
2. Description of the Prior Art.
Various types of equipment have been developed to support persons and objects on uneven terrains. Much of the prior equipment includes three legs, because three legs inherently provide stable support. Milk stools and camera tripods are well known examples of three-legged equipment used to stably support persons and objects, respectively.
To accommodate uneven terrains, some prior equipment included telescoping legs. Such equipment was undesirably expensive. In addition, trial and error was required to properly set the telescoping legs in order to attain a desired attitude for the person or object being supported.
Supporting a person in an upright attitude on uneven terrain is particularly important for hunters and fishermen. It is very uncomfortable to sit outdoors for even a short time unless the person is substantially upright. Consequently, seats and stands that can adjust to varying terrains are highly desirable to outdoorsmen.
An example of a prior attempt to solve the problems associated with sitting on uneven terrain is shown in U.S. Pat. No. 4,266,748. That patent describes a seat-supporting leg having a pointed free end that is insertable into the ground in a vertical attitude. The U.S. Pat. No. 4,266,748 patent also shows a variation in which three legs can pivot independently about a central tube. A cable connects the legs.
U.S. Pat. No. 4,934,638 shows multiple variations of a tripod stool with telescoping legs. U.S. Pat. No. 5,364,163 teaches a four-legged chair in which the two back legs are adjustable together relative to the front legs. U.S. Pat. No. 5,485,978 shows a three-legged stand with a seat on which a hunter can sit high above the ground.
U.S. Pat. No. 4,708,308 shows a portable stool in which three legs are independently pivotable about a support hub. The amount of pivoting of the legs is limited by a flexible cord.
British patent 1,598,812 discloses a support device useful for road signs and display boards. The British design includes three relatively pivotable legs tied together by a flexible chain.
Despite the availability of various seats and stands that can be used on uneven terrain, there nevertheless is room for further developments to them.
In accordance with the present invention, a versatile and convenient adjustable base structure is provided that stably supports persons and objects in an upright attitude on uneven terrain. This is accomplished by apparatus that includes a plate to which is connected the first ends of multiple independently and adjustably pivotable legs.
According to one aspect of the invention, there are four legs pivotally connected to the plate. Preferably, two first legs pivot in a first plane, and two second legs pivot in a second plane that is perpendicular to the first plane. The legs are selectively pivotable to a storage mode whereat they are generally parallel to each other and perpendicular to the plate. The legs are also pivotable to an operative mode whereat they diverge from the plate and each other. The amount of leg pivoting in the operative mode is limited by an endless flexible cable that connects the legs.
It is a feature of the invention that the legs can be pivotally connected to the plate in different ways. For example, the pivotal connections may include pairs of lugs that depend from the plate underside. A pin passing through a pair of lugs and the upper end of a leg completes the pivotal connection for that leg. Alternately, the plate may be notched for each leg. A pin held in the plate passes through the notch and a leg upper end to form the pivotal connection.
A foot of traction-type material is incorporated into the lower end of each leg. Also near the lower end of each leg is a pad. In the preferred embodiment, the pads are dome-shaped, with the concave sides of the pads facing the lower ends of the legs. The pads are swivelable on the legs. The pads swivel in the same planes in which the associated legs pivot relative to the plate. Each pad can be swiveled such that it lies in a plane that is approximately perpendicular to the associated leg. In that situation, the foot of leg lower end protrudes a short distance past the pad.
Upstanding from the plate top surface is a post with a flange adjacent the plate. A bushing joined to a carrier fits over the post and is axially supported by the flange. Alternately, the bushing may be in the plate, and the post is then part of the carrier. The carrier can be attached to any of a large number of standard components, such as commercially available boat seats. The bushing and post arrangement enable the carrier and seat to turn about the base structure. To best distribute the weight of a person sitting on the seat, the bushing or post is offset from the center of the carrier.
The individually pivotable legs enable the base structure to be used on ground or terrain of practically any contour. The legs are pivotable at different angles relative to the plate and to each other. Further, the plate can be oriented to be horizontal regardless of the angles of the various legs. The cable retains the legs in their desired locations regardless of any weight applied to the base structure. In that manner, a person sitting on the seat is upright and remains so as he turns the seat about the base structure. Instead of attaching to and supporting a boat seat or the like, the plate can be designed to removeably support a conventional chair, such as a lawn chair.
Further in accordance with the present invention, the total amount of pivoting of the legs is adjustable. For that purpose, at least one of the legs is hollow, and it includes multiple pairs of transverse holes through it. A first pair of holes receives the cable such that there is a length of the cable inside the hollow leg. One end of a tail is fastened to the cable length inside the leg. The other end of the tail emerges from the leg, as through a tail hole. Between the first pair of holes and the tail hole are a number of longitudinally spaced second pairs of transverse holes. A pin is removeably inserted into any of the second pair of holes between the cable length inside the leg and the first pair of holes. The pin has the effect of storing a portion of the cable inside the leg. Consequently, pivoting of the legs in the operative mode is adjustably limited by inserting the pin into different second pairs of holes.
If the support surface is hard, the feet on the legs lower ends bear the weight directly, and the pads do not come into use. If the ground is soft, however, the feet sink until the pads come into contact with the ground. The pads automatically swivel such that they lie in flat facing contact with the ground surface. The domed shape of the pads allows soft soil to fill in under the pads and thereby firmly grip the soil. The pads then bear the weight of the adjustable base structure and any person or object supported by it. The adjustable base structure of the invention is thus ideal for using in swampy or sandy soils.
The method and apparatus of the invention, using multiple legs independently and adjustably pivotable at respective upper ends about a plate, thus enables the plate to be oriented horizontally regardless of the contour of the supporting terrain. The pads virtually eliminate the probability that the plate will tilt during use, even though the base structure is used on soft soils. Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.